Frame structures, stent grafts incorporating the same, and methods for extended aortic repair

ABSTRACT

One aspect of the present disclosure can include a frame structure adapted for use with a stent graft. The frame structure can include a scallop region and a Z-form region. The scallop region can have a first end portion, a second end portion, and a perimeter that defines an aperture. The Z-form region can extend from the scallop region and include a plurality of Z-shaped struts, each of which has a first end and a second end that is connected to the scallop region at different points so as to form a central frame structure lumen. The second end portion of the scallop region can include a backstop that is deployable from a first flattened configuration to a second erect configuration. The backstop, in the second erect configuration, is sized and dimensioned to extend into a lumen of an aortic branch vessel.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/048,327, filed Sep. 10, 2014, the entirety of whichis hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates generally to vascular repair of bodilyvessels, and more particularly to frame structures, stent graftsincorporating the frame structures, and related methods for repairingaortic abnormalities.

BACKGROUND

A leading cause of disability and death in both the U.S. and abroadincludes damage to a portion of the vascular system. This is aparticular problem with regard to aortic aneurysms. Diseases of theaorta, for example, are becoming an increasing concern as a result ofadvancements in cardiac surgery and human longevity. Severe arterialsclerosis, severely calcified aorta, and other indications continue tonecessitate complete or partial aortic replacement procedures.

Aneurysms are typically characterized by diseased or damaged bloodvessels which lead to a weakening of the vessel wall. Weakening of thevessel wall can then lead to a blood-filled dilation of the vessel. Leftuntreated, aneurysms will eventually rupture and result in acute (andoften fatal) hemorrhaging in a very short period of time.

The aorta has numerous arterial branches. The arch of the thoracicaorta, for example, has three major branches arising from the convexupper surface of the arch and ascending through the superior thoracicaperture to the root of the neck. The proximity of an aneurysm to abranch artery may limit the use of an excluding device, such as atubular stent graft. For example, the main body or ends of a tubularstent graft may occlude or block the branch arteries as a result ofpositioning the stent graft against a healthy, i.e., non-diseased ordilated portion of the artery wall. Additionally, there may be aninadequate length of healthy tissue for the stent graft to seal againstin the area between the aneurysm and the location of the brancharteries. Even if the stent graft is initially located without blockinga branch artery, there still is a risk that the devices will migrate toa position where it may partially or fully block a branch artery.

SUMMARY

One aspect of the present disclosure can include a frame structureadapted for use with a stent graft. The frame structure can include ascallop region and a Z-form region. The scallop region can have a firstend portion, a second end portion, and a perimeter that defines anaperture. The Z-form region can extend from the scallop region andinclude a plurality of Z-shaped struts, each of which has a first endand a second end that is connected to the scallop region at differentpoints so as to form a central frame structure lumen. The second endportion of the scallop region can include a backstop that is deployablefrom a first flattened configuration to a second erect configuration.The backstop, in the second erect configuration, is sized anddimensioned to extend into a lumen of an aortic branch vessel.

Another aspect of the present disclosure can include a stent graft thatis movable between a collapsed configuration and an expandedconfiguration. The stent graft can comprise an elongated body having aproximal end portion, a distal end portion, an intermediate portionextending between the proximal and distal end portions, and a lumenextending between the proximal and distal end portions. The proximal endportion can include a frame structure, and the intermediate and distalend portions can include an expandable support member. Each of the framestructure and the expandable support member can have at least onesurface thereof covered by a biocompatible graft material. The proximalend portion can include an aperture that is in fluid communication withthe lumen, and is defined by a portion of the frame structure. The framestructure can include a deployable backstop configured to extend into alumen of an aortic arch branch vessel when the stent graft is implantedin a subject.

Another aspect of the present disclosure can include a method forrepairing at least a portion of a diseased aortic arch in a subject. Onestep of the method can include providing a stent graft. The stent graftcan include an elongated body having a proximal end portion, a distalend portion, an intermediate portion extending between the proximal anddistal end portions, and a lumen extending between the proximal anddistal end portions. The proximal end portion can include a framestructure, and the intermediate and distal end portions can include anexpandable support member. Each of the frame structure and theexpandable support member can have at least one surface thereof coveredby a biocompatible graft material. The proximal end portion can includean aperture that is in fluid communication with the lumen and defined bya portion of the frame structure. The main body can be positioned in thediseased portion of the aortic arch so that the frame structure islocated immediately adjacent the aortic arch branch vessels. Next, thebackstop can be deployed from a first flattened configuration into asecond erect configuration whereby the backstop extends into a lumen ofone of the aortic arch branch vessels. The main body can then besecurely implanted in the subject. The backstop, when located in thelumen of the aortic arch branch vessel, prevents migration of the stentgraft and provides a seal with the aortic arch branch vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomeapparent to those skilled in the art to which the present disclosurerelates upon reading the following description with reference to theaccompanying drawings, in which:

FIGS. 1A-B are schematic illustrations showing perspective views showinga stent graft in a collapsed configuration (FIG. 1A) and an expandedconfiguration (FIG. 1B) according to one aspect of the presentdisclosure;

FIG. 2 is a cross-sectional view of an aortic arch;

FIG. 3A is a schematic illustration showing a perspective view of aframe structure comprising the stent graft in FIG. 1B;

FIG. 3B is a schematic illustration showing a top view of the framestructure in FIG. 3A in a disassembled configuration;

FIG. 3C is a schematic illustration showing a side view of the framestructure in FIGS. 3A-B;

FIGS. 4A-B are schematic illustrations showing an alternativeconfiguration of the frame structure in FIGS. 3A-C;

FIG. 5A is a perspective view of an expandable support member comprisinga stent graft according to another aspect of the present disclosure;

FIG. 5B is a view taken from a proximal end portion of the expandablesupport member in FIG. 5A;

FIG. 5C is a top view of the expandable support member in FIG. 5A;

FIGS. 6A-B are perspective views showing transition of a backstopcomprising the stent graft in FIGS. 5A-C from a flattened configuration(FIG. 6A) to an erect configuration (FIG. 6B);

FIG. 7 is a process flow diagram illustrating a method for repairing atleast a portion of a diseased aortic arch according to another aspect ofthe present disclosure;

FIG. 8 is a perspective view showing the stent graft in FIG. 1A beinginserted into a diseased aortic arch;

FIG. 9 is a perspective view showing the backstop of the stent graft inFIG. 8 being deployed into a left subclavian artery; and

FIG. 10 is a perspective view showing the stent graft in FIG. 1Bsecurely implanted in the diseased aortic arch.

DETAILED DESCRIPTION Definitions

Unless otherwise defined, all technical terms used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich the present disclosure pertains.

In the context of the present disclosure, the singular forms “a,” “an”and “the” can include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises” and/or “comprising,” as used herein, can specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof.

As used herein, the term “and/or” can include any and all combinationsof one or more of the associated listed items.

As used herein, phrases such as “between X and Y” and “between about Xand Y” can be interpreted to include X and Y.

As used herein, phrases such as “between about X and Y” can mean“between about X and about Y.”

As used herein, phrases such as “from about X to Y” can mean “from aboutX to about Y.”

It will be understood that when an element is referred to as being “on,”“attached” to, “connected” to, “coupled” with, “contacting,” etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on,” “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” another feature may have portions thatoverlap or underlie the adjacent feature.

Spatially relative terms, such as “under,” “below,” “lower,” “over,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms can encompass different orientations of theapparatus in use or operation in addition to the orientation depicted inthe figures. For example, if the apparatus in the figures is inverted,elements described as “under” or “beneath” other elements or featureswould then be oriented “over” the other elements or features.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. Thus, a “first” element discussed below couldalso be termed a “second” element without departing from the teachingsof the present disclosure. The sequence of operations (or steps) is notlimited to the order presented in the claims or figures unlessspecifically indicated otherwise.

As used herein, the term “subject” can be used interchangeably with theterm “patient” and refer to any warm-blooded organism including, but notlimited to, human beings, pigs, rats, mice, dogs, goats, sheep, horses,monkeys, apes, rabbits, cattle, etc.

As used herein, the term “stent graft” can generally refer to aprosthesis comprising an expandable support member (e.g., a stent) and agraft material associated therewith that forms a lumen through at leasta portion of its length.

As used herein, the term “biocompatible” can refer to a material that issubstantially non-toxic in the in vivo environment of its intended use,and that is not substantially rejected by a patient's physiologicalsystem (i.e., is non-antigenic). This can be gauged by the ability of amaterial to pass the biocompatibility tests set forth in InternationalStandards Organization (ISO) Standard No. 10993 and/or the U.S.Pharmacopeia (USP) 23 and/or the U.S. Food and Drug Administration (FDA)blue book memorandum No. G95-1, entitled “Use of International StandardISO-10993, Biological Evaluation of Medical Devices Part-1: Evaluationand Testing.” Typically, these tests measure a material's toxicity,infectivity, pyrogenicity, irritation potential, reactivity, hemolyticactivity, carcinogenicity and/or immunogenicity. A biocompatiblestructure or material, when introduced into a majority of patients, willnot cause a significantly adverse, long-lived or escalating biologicalreaction or response, and is distinguished from a mild, transientinflammation which typically accompanies surgery or implantation offoreign objects into a living organism.

As used herein, the term “endoleak” can refer to the presence of bloodflow past the seal between the end of a stent graft and the vessel wall(Type I), and into the aneurysmal sac, when all such flow should becontained within the stent graft's lumen.

As used herein, the term “migration” can refer to displacement of astent graft from its intended implantation site.

As used herein, the terms “placed stent graft” or “implanted stentgraft” can refer to a surgically placed or implanted stent graft, eitherby invasive or non-invasive techniques.

Overview

The present disclosure relates generally to vascular repair of bodilyvessels, and more particularly to a stent graft and related method forrepairing aortic abnormalities. As representative of one aspect of thepresent disclosure, FIGS. 1A-B illustrate a stent graft 10 to facilitateextended repair in patients with vascular abnormalities, such as aorticdisease (e.g., aortic dissection or aneurysm). There is currentlygrowing interest in performing extended aortic repair at the time ofacute aortic dissection. No devices for doing so are currently availablein the U.S., and the device available in Europe requires a complexoperation to deploy it. As described in more detail below, aspects ofthe present disclosure allow for the extended repair technique (alsoknown as the frozen elephant trunk technique) to be more widely adapted,while also permitting better repair of the aorta during an emergencyprocedure. It will be appreciated that aspects of the present disclosuremay also be used to treat vascular trauma, arteriosclerosis,calcification, microbial infection, congenital defects, and otherobstructive diseases associated with the aorta.

To assist the reader in understanding the relevant anatomy andphysiology to which certain aspects of the present disclosure pertain,FIG. 2 illustrates a cross-sectional view of a human aortic arch 12,including the aortic arch branch vessels 14. The aorta is the largestvessel in the body. It transports oxygenated blood from the leftventricle of the heart (not shown) to every organ. The aorta starts inthe heart with the aortic valve 16, which is immediately adjacent theaortic root 18 and followed by the ascending aorta 20, the transverseaorta 12 or aortic arch, the descending aorta 22, and thethoracoabdominal aorta (not shown). The aorta ends in the abdomen afterbifurcation of the abdominal aorta in the two common iliac arteries (notshown). The aortic arch 12 gives off the brachiocephalic trunk 24, theleft common carotid artery 26, and the left subclavian artery 28. Thebrachiocephalic trunk 24 splits to form the right subclavian and theright common carotid arteries 30 and 32, which supply blood to the rightarm and the right side of the neck and head. The left common carotidartery 26 and left subclavian artery 28 perform parallel functions onthe left side.

Frame Structures

One aspect the present disclosure can include frame structures adaptedfor use with a stent graft. The frame structures can be self-expanding,stent-like structures configured to transition from a collapsedconfiguration (e.g., during delivery) to an expanded configuration(e.g., upon implantation). The frame structures can be made from one ora combination of elastic or superelastic materials, such as Nitinol,Cobalt Chromium, and 316L Stainless steel. In some instances, the framestructures can be formed using one or more lasercutting steps (e.g.,using a thermal femtosecond laser to cut an appropriately-sized Nitinolsheet). The cut frame structure can then be applied to a shape-settingmandrel and treated (e.g., heated to about 350° C., baked for about 10minutes, and then quenched in room temperature water) to obtain adesired configuration. The frame structures can be formed from a single,unitary wire or from two or more wires.

Examples of frame structures are illustrated below. Generally speaking,the frame structures can include a scallop region and a Z-form regionextending therefrom. The scallop region can have a first end portion, asecond end portion, and a perimeter that defines an aperture. The Z-formregion can extend from the scallop region and comprise a plurality ofZ-shaped struts. Each of the Z-shaped struts has a first end and asecond end that extends from, or is connected to, the scallop region ata different point so as to form a central frame structure lumen. Thesecond end portion of the scallop region includes a backstop that isdeployable from a first flattened configuration to a second erectconfiguration. In the second erect configuration, the backstop can besized and dimensioned to extend into a lumen of an aortic branch vessel.In one example, the backstop 36 can have a width of about 3 mm to about15 mm or more (e.g., about 6 mm to about 9 mm, such as 8 mm) and aheight of about 2 mm to about 3 cm or more (e.g., about 10 mm).Advantageously, the ability of the backstop to extend into the lumen ofan aortic arch branch vessel 14 prevents migration of a stent graftassociated with the frame structure once implanted. Additionally, thebackstop advantageously optimizes the seal formed between an associatedstent graft and the aortic arch branch vessel 14 (that receives thebackstop), which may be vulnerable to endoleaks and where tears incomplex dissections often occur.

One example of a frame structure 30 for use with a stent graft isillustrated in FIGS. 3A-C. The frame structure 30 can have anarch-shaped centerline 32 (FIG. 3C) that mirrors the arch-shapedcenterline of an aortic arch 12. In other words, the centerline 32 ofthe frame structure 30 has an arcuate shape (e.g., a radius of curvaturethat is equal or about equal to the radius of curvature of the aorticarch 12). The arch-shaped centerline 32 advantageously allows the framestructure 30 (and a stent graft associated therewith) to conform to theaortic arch 12 and ensure proper sealing, once implanted, to avoidendoleaks. The arch-shaped centerline 32 is achieved, at least in part,by the spacing associated with Z-shaped struts 34 that form a Z-region36 of the frame structure 30. As shown in FIG. 3C, for example, thedistance D1 between the struts 34 at an upper portion 38 of the Z-formregion 36 is greater than the distance D2 between the same struts at alower portion 40 of the Z-form region. The difference between D1 and D2creates a taper from the upper portion 38 to the lower portion 40 that,in turn, results in the arch-shaped centerline 32.

Referring to FIGS. 3A-B, the frame structure 30 can comprise a scallopregion 42 and a Z-form region 38 extending therefrom. As discussedbelow, the profile of the scallop region 41 advantageously allows for abalance of strength and stretch in the region around the ascendingvessels of the aortic arch 12. The scallop region 42 can have a firstend portion 44, a second end portion 46, and a perimeter 48 that definesan aperture 50. The aperture 50 is sized and dimensioned to surround theorigins of each of the supra-aortic vessels. In some instances, theaperture 50 can have a length of about 20-50 mm (e.g., 42 mm) and awidth of about 9-20 mm (e.g., 14-15 mm). The scallop region 42 can beformed from a single wire or from two or more wires. The wire(s) formingthe scallop region 42 can form a continuous or discontinuous ring. Asshown in FIGS. 3A-B, for example, a single wire forming the scallopregion 42 can form a discontinuous ring such that first and second freeends 52 and 54 are located at the first end portion 44. In this case,the first and second free ends 52 and 54 terminate as loop-shapedstructures that facilitate attachment of the frame structure 30 to agraft material.

The scallop region 42 can comprise a plurality of attachment members 56that are spaced apart from one another by one or more peak-shapedstructures 58. In one example, one or more (e.g., all) of the attachmentmembers 56 can be omega-shaped and include an arcuate segment 60 that isfree from direct attachment to any of the Z-shaped struts 34. By “freefrom direct attachment to any of the Z-shaped struts 34”, it is meantthat at last one intervening structure (e.g., a peak-shaped structure58) is located between the arcuate segment 60 of the attachment member56 and a Z-shaped strut 34. Advantageously, attachment members 56 havingan omega-shaped configuration permit a high degree of stretch as aresult of having a longer length over which to spread out the force(essentially a softer spring constant). In one example, the scallopregion 42 can include eight omega-shaped attachment members 56. Theattachment members 56 can facilitate attachment of the frame structure30 to a graft material (e.g., by receiving one or more fasteners, suchas sutures and/or ETV clips) therethrough. The attachment members 56 canbe evenly or unevenly spaced apart from one another or from thepeak-shaped structures 58.

The peak-shaped structures 58 comprising the scallop region 42 can havea V-shaped, U-shaped, or arch-shaped configuration. The peak-shapedstructures 58 comprising the scallop region 42 can have the same ordifferent configuration, such as those just mentioned. Each peak-shapedstructure 58 can be comprised of two straight segments 62 that convergeat an apex 64. A Z-shaped strut 34 can extend from, or be directlyconnected to, an apex 64 of each peak-shaped structure 58. In oneexample, the scallop region 42 can include six peak-shaped structures58. Advantageously, the transition of the scallop region 42 into theZ-form region 36 at the peak-shaped structures 58 facilitatescompression of the frame structure 30 (and associated stent graft) intoa delivery catheter, as with a conventional stent graft.

The second end portion 46 of the scallop region 42 can include abackstop 66. The backstop 66 can be comprised of the same or differentwire(s) as the wire(s) comprising the rest of the scallop region 42. Thebackstop 66 is deployable from a first flattened configuration (FIG. 3B)to a second erect configuration (FIGS. 3A and 3C), one example of whichis illustrated in FIGS. 6A-B. Methods for deploying the backstop 66 arediscussed below. Generally, however, the backstop 66 can be deployedautomatically (e.g., by “popping up” upon removal of a constrainingmaterial thereon) or manually (e.g., by actuation of a pullwire or othersimilar mechanism). In the flattened configuration, the backstop 66 canextend in a coaxial or substantially coaxial manner relative to thecenterline 32 of the frame structure 30. In the erect configuration, thebackstop 66 can extend radially away from the scallop region 42. In thesecond erect configuration, the backstop 66 can be sized and dimensionedto extend into a lumen of an aortic branch vessel (e.g., the leftsubclavian artery 28). Advantageously, the backstop 66, when deployed inthe second erect configuration, improves anchoring and sealing of astent graft associated therewith.

The second end portion 46 of the scallop region 42 can further includeat least one extension segment 68 that connects, and extends between,the backstop 66 and an attachment member 56. The extension segment 68comprises an additional length that allows for a longer flexing area,thereby reducing strain and allowing use of a superelastic material(e.g., Nitinol) without any plastic deformation. As shown in FIG. 3A,the second end portion 46 of the scallop region 42 can include first andsecond extension segments 68, each of which has an arcuate configurationand extends between the backstop 66 and a respective attachment member56.

The Z-form region 36 can extend from, or be directly connected, to thescallop region 42. The Z-form region 36 can comprise a plurality ofZ-shaped struts 34. Advantageously, the use of Z-shaped struts 34 toform the Z-form region 36 allows for a balance of radial strength andcompressibility of the frame structure 30. Each of the Z-shaped struts34 has a first end 70 and a second end 72 (FIG. 3B). The first andsecond ends 70 and 72 can extend from, or be connected to, differentpoints of the scallop region 42 so as to form a central frame structurelumen 74. For example, a first end 70 of a Z-shaped strut 34 can beconnected to, or extend from, a first peak-shaped structure 58, and asecond end 72 of the same Z-shaped strut can be connected to, or extendfrom, a second different peak-shaped structure of the scallop region 42.In one example, the Z-form region 36 can be comprised of three Z-shapedstruts 34. It will be appreciated that the thickness, number, andspacing between the Z-shaped struts 34 comprising the Z-form region 36can be adjusted as needed.

In one example of the present disclosure, the frame structure 30 can becomprised of one or more Nitinol wires and include eight omega-shapedattachment members 56, six peak-shaped structures 58, and three Z-shapedstruts 34.

An alternative configuration of a frame structure 76 is shown in FIGS.4A-B. The frame structure 76 can be identically constructed as the framestructure 30 shown in FIGS. 3A-B, except where described below. Thus,structures with the same reference numbers in FIGS. 4A-B are identicalto the structures with the same reference number in FIGS. 3A-B, whereasdifferent structures use different reference numbers. The framestructure 76 (FIGS. 4A-B) can comprise a scallop region 78 and a Z-formregion 36 connected to or extending therefrom. The scallop region 78 canhave a first end portion 80, a second end portion 82, and a perimeter 84that defines an aperture 86. The Z-form region 36 can extend from thescallop region 78 and comprise a plurality of Z-shaped struts 34. Eachof the Z-shaped struts 34 has a first end 70 and a second end 72 thatextends from, or is connected to, the scallop region 78 at a differentpoint so as to form a central frame structure lumen 74. The second endportion 82 of the scallop region 78 includes a backstop 66 that isdeployable from a first flattened configuration to a second erectconfiguration. In the second erect configuration, the backstop 66 can besized and dimensioned to extend into a lumen of an aortic branch vessel.

Unlike the scallop region 42 in FIGS. 3A-B, attachment members 88comprising the scallop region 78 can be peak-shaped (e.g., V-shaped,U-shaped, or arch-shaped). Each attachment member 78 can be comprised oftwo straight segments 90 that converge at an apex 92. Each attachmentmember 88 can have a length L1 that extends from a base to the apex 92.A Z-shaped strut 34 can extend from, or be directly connected to, theapex 92 of each attachment member 88. In one example, the scallop region78 can include six peak-shaped attachment members 88.

Each of the peak-shaped attachment members 88 can be spaced apart fromone another by first and second peak-shaped structures 94′ and 94″. Eachof the peak-shaped structures 94′ and 94″ can be V-shaped, U-shaped, orarch-shaped. Each of the peak-shaped structures 94′ and 94″ can becomprised of two straight segments 96 that converge at an apex 98. Eachof the peak-shaped structures 94′ and 94″ can have a length L2 thatextends from a base to an apex thereof 98. In some instances, the lengthL2 of each peak-shaped structure 94′ and 94″ is the same. In otherinstances, the length L2 of at least one peak-shaped structure 94′ isdifferent than the length L2 of one or more of the other peak-shapedstructures 94″. As shown in the exploded window of FIG. 4A, the lengthL1 of the attachment member 88 can be greater than the length L2 of eachof the first and second peak-shaped structures 94′ and 94″.

An alternative configuration of a frame structure 100 is shown in FIGS.5A-6B. The frame structure 100 can be identically constructed as theframe structures 30 and 76 shown in FIGS. 3A-B and FIGS. 4A-B,respectively, except where described below. Thus, structures with thesame reference numbers in FIGS. 3A-B and FIGS. 4A-B are identical to thestructures with the same reference number in FIGS. 5A-6B, whereasdifferent structures use different reference numbers. The framestructure 100 (FIGS. 5A-6B) can comprise a scallop region 102 and aZ-form region 36 extending therefrom. The scallop region 102 can have afirst end portion 104, a second end portion 106, and a perimeter 108that defines an aperture 110. The Z-form region 36 can extend from thescallop region 102 and comprise a plurality of Z-shaped struts 34. Eachof the Z-shaped struts 34 has a first end 70 and a second end 72 thatextends from, or is connected to, the scallop region 102 at a differentpoint so as to form a central frame structure lumen 74. The second endportion 106 of the scallop region 102 includes a backstop 66 that isdeployable from a first flattened configuration to a second erectconfiguration. In the second erect configuration, the backstop 66 can besized and dimensioned to extend into a lumen of an aortic branch vessel.

Unlike the scallop regions 42 and 78 discussed above, the scallop region102 of the frame structure 100 shown in FIGS. 5A-6B can comprise acontinuous, ring-shaped wire 112. The Z-shaped struts 34 comprising theZ-form region 36 can be directly connected to, or extend from, the wire112. Similarly, the backstop 66 can be directly connected to, or extendfrom, the wire 112. Integration of the frame structure 100 into a stentgraft is described below.

Stent Grafts

Another aspect of the present disclosure can include a stent graft forimplantation in a diseased blood vessel, such as a diseased aortic arch12. The stent graft can be movable between a collapsed configuration andan expanded configuration. The stent graft can comprise an elongatedbody having a proximal end portion, a distal end portion, anintermediate portion extending between the proximal and distal endportions, and a lumen extending between the proximal and distal endportions. The proximal end portion can include a frame structure, andthe intermediate and distal end portions can include an expandablesupport member. As discussed below, the frame structure can beconfigured as any one or combination of the frame structures discussedabove. Each of the frame structure and the expandable support member canhave at least one surface thereof covered by a biocompatible graftmaterial. The proximal end portion can include an aperture that is influid communication with the lumen, and is defined by a portion of theframe structure. The frame structure can include a deployable backstopconfigured to extend into a lumen of an aortic arch branch vessel whenthe stent graft is implanted in a subject.

One example of a stent graft 114 is shown in FIGS. 1A-B. In thisexample, the stent graft 114 can have a flexible, tube-likeconfiguration and be adapted for placement in a bodily vessel, such asan aortic arch 12. The stent graft 114 can be configured to engage aninner surface of a bodily vessel so that an elongated body 116 thereofforms a substantial seal with the inner surface of the bodily vessel.The stent graft 114 can be compressed to facilitate delivery to a bodilyvessel, and then selectively expanded by, for example, a deploymentmechanism 118 (e.g., a balloon, stent, etc.) so that the stent graftsubstantially conforms to the inner surface of the bodily vessel. Asshown in FIG. 1B, the elongated body 116 can include a proximal endportion 120 defining a first opening 122, a distal end portion 124defining a second opening (not shown), an intermediate portion 126extending between the proximal and distal end portions, and a lumen 128extending between the proximal and distal end portions. In someinstances, the proximal end portion 120 of the body 116 can include asewing ring (not shown) attached thereto. The sewing ring can have acircular or oval-like shape and be adapted for suturing to a portion ofa bodily vessel, such as a portion of an aortic arch 12. The sewing ringcan be securely attached to the body 116 of the stent graft 114 usingany one or combination of known attachment means (e.g., staples, clips,sutures, adhesives, etc.). The sewing ring can be comprised of anysuitable biocompatible material including, for example, woven polyester,DACRON, TEFLON, PTFE and/or any one or combination of the biocompatiblematerials disclosed below.

In another aspect, the proximal end portion 120 of the elongated body116 can include a frame structure 30 or 76. The intermediate portion 126and the distal end portion 124 of the elongated body 116 can include anexpandable support member 130. Each of the frame structure 30 or 76 andthe expandable support member 130 can be stitched into graft material132 comprising the stent graft 114. Each of the frame member 30 or 76and the expandable support member 130 can have at least one surfacethereof covered by the graft material 132 (e.g., a biocompatible graftmaterial). The graft material 132 can include any biocompatible materialthat is mechanically stable in vivo and is capable of preventing orsubstantially reducing the possibility of the passage or flow of bloodor other body fluids through the stent graft 114. Examples of suitablematerials for use in constructing the stent graft 114 can includebiocompatible plastics, such as woven polyester, non-resorbableelastomers or polymers such as silicone, SBR, EPDM, butyl, polyisoprene,Nitril, Neoprene, nylon alloys and blends, poly(ethylene-vinyl-acetate)(EVA) copolymers, silicone rubber, polyamides, polyurethane, poly(esterurethanes), poly(ether urethanes), poly(ester urea), polypropylene,polyethylene, polycarbonate, polytetrafluoroethylene (PTFE) (e.g.,TEFLON), expanded PTFE (ePTFE), polyethylene terephthalate (e.g.,DACRON), and polyethylene copolymers. It will be appreciated that thestent graft 114 can additionally or optionally include a layer ofbiological material (not shown), such as bovine or equine pericardium,peritoneal tissue, an allograft, a homograft, a patient graft, or acell-seeded tissue. The layer can cover the entire stent graft 114 oronly a portion thereof. One skilled in the art will appreciate thatother materials suitable for vascular surgical applications may also beappropriate for the stent graft 114.

In another aspect, the expandable support member 130 can have an innersurface (not shown in detail) that defines a lumen (not shown). In someinstances, the expandable support member 130 can have a single, unitaryconfiguration, whereas in other instances, the expandable support membercan be comprised of a series of discrete units (e.g., each unit having aZ-stent configuration) (not shown). The structure of the expandablesupport member 130 may be a mesh, a zigzag wire, diamond-shaped, aspiral wire, an expandable stent, or other similar configuration thatallows the expandable support member to be collapsed and expanded. Theexpandable support member 130 can be comprised of a material having ahigh modulus of elasticity, including, for example, cobalt-nickel alloys(e.g., Elgiloy), titanium, nickel-titanium alloys (e.g., Nitinol),cobalt-chromium alloys (e.g., Stellite),nickel-cobalt-chromium-molybdenum alloys (e.g., MP35N), graphite,ceramic, stainless steel, and hardened plastics. The expandable supportmember 130 may also be made of a radio-opaque material or includeradio-opaque markers (not shown) to facilitate fluoroscopicvisualization. Examples of radio-opaque materials are known in the artand can include, but are not limited to, gold, gallium, technetium,indium, strontium, iodine, barium, bromine and phosphorus-containingcompounds. As described in more detail below, radio-opaque markers canbe used to facilitate implantation of the stent graft 114 in a bodilyvessel.

In another aspect, the stent graft 114 can include an aperture 134 atleast partly or entirely defined by the aperture 50 or 84 of the scallopregion 42 or 78. For example, the aperture 134 can be located about anupper portion 136 of the proximal end portion 120. The aperture 134 canbe sized and dimensioned so that the lumen 128 of the elongated body 116is in fluid communication with the lumen of each of the aortic archbranch vessels 14 when the stent graft 114 is implanted in a subject.The aperture 134 can have any desired length and width sufficient topromote leak-proof attachment of the aortic arch branch vessels 14 tothe elongated body 116. In some instances, the aperture 134 can have anelongated, oval-like shape; however, it will be appreciated that othershapes are possible.

In another aspect, and as discussed above, the backstop 66 can beself-expanding and thereby automatically deploy during expansion of thestent graft 114. In other instances, a deployment mechanism (not shown)(e.g., a pullwire) may be used to selectively deploy the backstop 66. Asshown in FIGS. 6A-B, for instance, the backstop 66 can have alongitudinal axis LA_(s). When the stent graft 114 is in the collapsedconfiguration, the backstop 66 can be positioned such that thelongitudinal axis LA_(s) is parallel to, or substantially parallel to, alongitudinal axis LA_(m) of the elongated body 116 (FIG. 6A). In theexpanded configuration, the longitudinal axis LA_(s) of the backstop 66can be tangential (e.g., orthogonal) to the longitudinal axis LA_(m) ofthe elongated body 116 (FIG. 6B). The backstop 66 can be automaticallyor manually deployed. To provide for automatic deployment, the elongatedbody 116 of the stent graft 114 can include a detachable strip 138 (FIG.1A). The detachable strip 138 can include a section of material thatoverlies the aperture 134 and the backstop 66 when the elongated body116 is in the collapsed configuration. The detachable strip 138 can bemade of the same or a different material as the graft material 132 ofthe stent graft 114, so long as the detachable strip can be easilyremoved (e.g., by tactile force). Thus, in some instances, thedetachable strip 138 can have a perimeter defined by a series ofperforations (not shown) that permit easy removal of the detachablestrip from stent graft 114. As described in more detail below, thedetachable strip 138 can be peeled away from the elongated body 116(e.g., in a distal-to-proximal direction). Upon doing so, the backstop66 can automatically “pop-up” and obtain a deployed configurationwhereby the longitudinal axis LA_(s) of the backstop 66 is tangential tothe longitudinal axis LA_(m) of the elongated body 116. The detachablestrip 138 can be further peeled away from the elongated body 116 toexpose the aperture 134.

Another example of a stent graft 140 according to the present disclosureis illustrated in FIGS. 5A-C. The stent graft 140 can be identicallyconstructed as the stent graft 114 shown in FIGS. 1A-B, except wheredescribed below. Thus, structures with the same reference numbers inFIGS. 1A-B are identical to the structures with the same referencenumber in FIGS. 5A-C, whereas different structures use differentreference numbers. The stent graft 140 can be movable between acollapsed configuration and an expanded configuration. The stent graft140 can comprise an elongated body 142 having a proximal end portion144, a distal end portion 124, an intermediate portion 126 extendingbetween the proximal and distal end portions, and a lumen 146 extendingbetween the proximal and distal end portions. The proximal end portion144 can include a frame structure 100, and the intermediate portion 126and the distal end portion 124 can include an expandable support member130. Each of the frame structure 100 and the expandable support member130 can have at least one surface thereof covered by a biocompatiblegraft material 132. The proximal end portion 144 can include an aperture148 that is in fluid communication with the lumen 146, and is defined bya portion of the frame structure 100. The frame structure 100 caninclude a deployable backstop 66 configured to extend into a lumen of anaortic arch branch vessel when the stent graft 140 is implanted in asubject.

Unlike the stent graft 114 in FIGS. 1A-B, the proximal end portion 144of the stent graft 140 can have a basket-like configuration (e.g., byvirtue of the frame structure construction) when the elongated body 142is in the expanded configuration. The cross-sectional profile of theproximal end portion 144 can be asymmetrical. As shown in FIG. 5B, forexample, an upper portion 150 of the proximal end portion 144 can have awidth W1 that is greater than the width W2 of a lower portion 152 of theproximal end portion. The asymmetric cross-sectional profile can promoteoptimal seal formation between the greater and lesser curves of theaortic arch 12 and the upper and lower portions 150 and 152,respectively, of the proximal end portion 144. Consequently, the shapeof the proximal end portion 144 promotes movement of blood through thestent graft 140 while maintaining patency of the lumen 146. Thestructure of the proximal end portion 144 may be the same or differentthan the structure of the rest of the elongated body 142. To accommodatethe basket-shape configuration of the proximal end portion 144, forexample, the frame structure 100 of the proximal end portion can includeZ-shaped struts 34 oriented in the opposite direction from the rest ofthe expandable support member 130, a coil-like configuration, or someother self-expanding weave.

Methods

Another aspect of the present disclosure can include a method 154 forrepairing a diseased blood vessel in a subject, such as an aneurysm ofthe aortic arch 12. The method 154 can include the steps of: providing astent graft (Step 156); positioning the stent graft in a diseased aorticarch of a subject so that a backstop thereof is located immediatelyadjacent the aortic arch branch vessels (Step 158); deploying thebackstop (Step 160); and securely implanting the stent graft in thesubject (Step 162). In some instances, the method 154 can be used totreat DeBakey type I acute aortic dissections. For example, the method154 can be adapted based on the procedure of Roselli et al., J ThoracCardiovasc Surg., 145(3 Suppl):S197-201 (March 2013). The method 154 canalso be used for repair of thoracic aorta disease in both ascending archand descending thoracic aorta (Svensson et al., Ann Thorac Surg.,96:548-58 (2013).

To repair an aortic arch aneurysm, for example, an open-chest frozenelephant trunk procedure using the stent graft 114 shown in FIGS. 1A-Bcan be employed. Although implantation of the stent graft 114 isdescribed below using an open surgical approach, it will be appreciatedthat other methods for implanting the stent graft, such as apercutaneous or minimally invasive surgical technique may be used, aswell as other configurations of the stent graft described herein.

After providing a stent graft 114 at Step 156, a placement position forthe stent graft in the aortic arch 12 can be determined using a knownimaging technique, such as fluoroscopy, angiography, ultrasonography,CT, helical CT, CT angiogram, MRI, and/or MR angiography. Prior toimplanting the stent graft 114, the stent graft can be loaded onto adelivery mechanism 118 to facilitate delivery of the stent graft to theaortic arch 12 in the collapsed configuration. After loading the stentgraft 114 onto the delivery mechanism 118, the delivery mechanism can beinserted into the aortic arch 12 via an incision (not shown). As shownin FIG. 8, the delivery mechanism 18 can be positioned in the aorticarch 12 so that a detachable strip 138 is positioned immediately ordirectly adjacent the aortic arch branch vessels 14 (Step 158). Once thedelivery mechanism 118 and the stent graft 114 are appropriatelypositioned in the aortic arch 14, the detachable strip 138 can be peeledaway from the elongated body 116 in a distal-to-proximal direction (Step160). As the detachable strip 138 is progressively peeled away(indicated by arrow in FIG. 9), the backstop 66 automatically “pops-up”and obtains the deployed erect configuration. In the erectconfiguration, all or only a portion of the backstop 66 extends into thelumen of an aortic arch branch vessel 14, such as the left subclavianartery 28. In some instances, at least a portion of the backstop 66 canbe in physical contact with a portion of the left subclavian artery 28,such as the origin of the left subclavian artery. The detachable strip138 can then be further peeled away from the elongated body 116 toexpose the aperture 134.

After the detachable strip 138 has been completely removed from thestent graft 114, the rest of the elongated body 116 can be expanded asshown in FIG. 10. In the expanded configuration, the lumen of each ofthe aortic arch branch vessels 14 can be in fluid communication with thelumen 128 of the stent graft 114. Thereafter, the incision in the aorticarch 12 can be closed and the vessels surrounding the stent graft 114unclamped so that blood can flow normally through the stent graft.Conventional stent grafts, once implanted, often suffer from migrationdue to pulsatile blood flow, non-optimal construction, etc.Advantageously, the backstop 66 can prevent migration of the stent graft114 once implanted by resisting the flow of blood through the aorta. Itwill be appreciated that expansion and implantation of the stent graft114 may be varied as needed. In some instances, for example, thebackstop 66 can be constrained until the entire elongated body 116 isexpanded. In other instances, a portion of the stent graft 114 (e.g.,the proximal end portion 120) may first be expanded, advanced into theaorta, and then the remainder of the stent graft expanded.

From the above description of the present disclosure, those skilled inthe art will perceive improvements, changes and modifications. Forexample, it will be appreciated that the order of steps described abovefor implanting the stent graft 114 are intended to be illustrative onlyand are not intended to limit the present disclosure to the order ofsteps described herein. Such improvements, changes, and modificationsare within the skill of the art and are intended to be covered by theappended claims. All patents, patent applications, and publicationscited herein are incorporated by reference in their entirety.

The following is claimed:
 1. A frame structure adapted for use with a stent graft, the frame structure comprising: a scallop region having a first end portion, a second end portion, and a perimeter that defines an aperture; and a Z-form region extending from the scallop region and comprising a plurality of Z-shaped struts, each of which has a first end and a second end that is connected to the scallop region at different points so as to form a central frame structure lumen, wherein the scallop region includes a plurality of attachment members spaced apart from one another by one or more peak-shaped structures; wherein the second end portion of the scallop region includes a backstop that is deployable from a first flattened configuration to a second erect configuration; wherein the backstop, in the second erect configuration, is sized and dimensioned to extend into a lumen of an aortic branch vessel.
 2. The frame structure of claim 1, having an arch-shaped centerline that mirrors the arch-shaped centerline of an aortic arch.
 3. The frame structure of claim 1, wherein each of the attachment members is omega-shaped and includes an arcuate portion that is free from direct attachment to any of the Z-shaped struts.
 4. The frame structure of claim 1, wherein each of the peak-shaped structures includes an apex that is connected to the first or second of one of the Z-shaped struts.
 5. The frame structure of claim 1, wherein each of the attachment members is peak-shaped.
 6. The frame structure of claim 1, wherein each of the peak-shaped attachment members is spaced apart from one another by first and second peak-shaped structures, each of the first and second peak-shaped structures having an apex that is free from direct attachment to any of the Z-shaped struts.
 7. A stent graft that is movable between a collapsed configuration and an expanded configuration, the stent graft comprising: an elongated body having a proximal end portion, a distal end portion, an intermediate portion extending between the proximal and distal end portions, and a lumen extending between the proximal and distal end portions, the proximal end portion including a frame structure and the intermediate and distal end portions including an expandable support member, each of the frame structure and the expandable support member having at least one surface thereof covered by a biocompatible graft material; wherein the proximal end portion includes an aperture that is in fluid communication with the lumen and defined by a portion of the frame structure, the frame structure including a deployable backstop configured to extend into a lumen of an aortic arch branch vessel when the stent graft is implanted in a subject; wherein the backstop extends radially away from the main body when the stent graft obtains the expanded configuration.
 8. The stent graft of claim 7, wherein the covering further includes a detachable strip that overlies the aperture and the backstop when the stent graft is in the collapsed configuration.
 9. The stent graft of claim 8, wherein the backstop is automatically deployed upon removal of the detachable strip from over the backstop.
 10. The stent graft of claim 7, wherein the aperture is sized and dimensioned so that the lumen of the main body is in fluid communication with the lumen of each of the aortic arch branch vessels when the stent graft is implanted in a subject.
 11. The stent graft of claim 7, wherein the stent frame further comprises: a scallop region having a first end portion, a second end portion, and a perimeter that defines an aperture; and a Z-form region extending from the scallop region and comprising a plurality of Z-shaped struts, each of which has a first end and a second end that is connected to the scallop region at different points so as to form a central frame structure lumen; wherein the second end portion of the scallop region includes the backstop.
 12. The stent graft of claim 11, wherein the frame structure has an arch-shaped centerline that mirrors the arch-shaped centerline of an aortic arch.
 13. A stent graft that is movable between a collapsed configuration and an expanded configuration, the stent graft comprising: an elongated body having a proximal end portion, a distal end portion, an intermediate portion extending between the proximal and distal end portions, and a lumen extending between the proximal and distal end portions, the proximal end portion including a frame structure and the intermediate and distal end portions including an expandable support member, each of the frame structure and the expandable support member having at least one surface thereof covered by a biocompatible graft material; wherein the proximal end portion includes an aperture that is in fluid communication with the lumen and defined by a portion of the frame structure, the frame structure including a deployable backstop configured to extend into a lumen of an aortic arch branch vessel when the stent graft is implanted in a subject; wherein the aperture is sized and dimensioned so that the lumen of the main body is in fluid communication with the lumen of each of the aortic arch branch vessels when the stent graft is implanted in a subject; wherein the aperture is sized and dimensioned so that the lumen of the main body is in fluid communication with the lumen of each of the aortic arch branch vessels when the stent graft is implanted in a subject. 